The present invention relates to a final drive supporting structure for supporting a final drive assembly to a vehicle body, and more specifically to a final drive supporting structure designed to minimize tilting movement of a drive pinion shaft of the final drive assembly to reduce vibrations and noise.
A final drive assembly is suspended resiliently and flexibly from a vehicle body in order to isolate vibrations and noise due to a reaction torque about a drive pinion axis and a reaction torque about a drive axle. A U.S. Pat. No. 4,699,230 (corresponding to Japanese Patent Provisional Publication No. 61-125924) discloses a final drive suspension structure having at least two elastic suspension elements for supporting a final drive assembly on a vehicle body. The support positions and stiffnesses (or rigidities) of the elastic suspension elements are so determined that one of the suspension positions is away from a torque support plane of a torque (a resulting torque of a starting torque and a propeller shaft torque) determined by the other suspension element, and that swivel movements of the same magnitude are produced in opposite directions at a connecting point between the propeller shaft and the drive pinion shaft. Therefore, this suspension structure can prevent displacement of the connection point which is subject to influences of the starting torque and propeller shaft torque, and improve the durability of the joint between the drive pinion shaft and propeller shaft.
However, this conventional suspension structure is unable to sufficiently prevent angular displacement (inclination) of the axis of the drive pinion shaft. Especially, the inclination of the axis of the drive pinion shaft increases the vibrations and noise produced by a secondary couple due to a joint angle of a universal joint of the propeller shaft.